JP4885932B2 - Granule fluidity measuring apparatus and method - Google Patents

Description

  The present invention relates to an apparatus and method for accurately measuring the fluidity of a granular material having a relatively large particle diameter of 45 to 850 μm.

For example, in the production of MOX fuel for fast breeder reactors, MOX (mixed oxide of Pu02 and U02) particles of several hundred microns are produced from a mixed solution of uranyl nitrate and plutonium nitrate received from the reprocessing process, and the next process In order to obtain a good molded body, it is necessary to uniformly fill the particles. For this purpose, it is necessary to accurately measure the fluidity of MOX particles. As a device for accurately measuring the fluidity of a granular material such as MOX particles, a vibrating capillary type granular material fluidity evaluation device has been known (see Patent Document 1).
WO 2006/115145 A1

  However, the conventional particle fluidity measuring apparatus is effective for measuring a relatively small particle having a particle diameter smaller than 250 μm, but the particle diameter is 250 μm or more like MOX particles after granulation. In the case of a granular material having a relatively large diameter, the fluidity cannot always be measured accurately.

  The object of the present invention is to measure the fluidity of a granular material that can accurately measure the fluidity of a granular material containing relatively large particles with a particle size of up to 850 μm, such as MOX particles after granulation. To provide an apparatus.

The present invention is a method for measuring the fluidity of a granular material using a vibrating capillary type granular material fluidity evaluation apparatus. In this method, the narrow tube is vibrated at an angle of 20 ° with respect to the vertical, and the fine tube has a particle size of 45 μm to 850 μm, and is a particle to be measured having a particle size of at least 600 μm to 850 μm. Supplying a certain amount of the granular material to be measured including the body, measuring the amplitude of the vibration of the thin tube, and the weight of the granular material discharged from the discharge port having a diameter of 3 mm to 4 mm of the thin tube; Based on the measured value, the fluidity of the granular material is obtained.

In the above-described powder particle fluidity measurement method, the powder particles are preferably MOX particles granulated in the reprocessing step.

  The granular material fluidity measuring apparatus and method according to the present invention are suitable for measuring the fluidity of granular materials having a particle size in the range of 45 μm to 850 μm, and are particularly granulated in the reprocessing step of spent nuclear fuel. This is suitable for measuring the fluidity of MOX (mixed oxide of PuO2 and UO2) particles.

  In the present invention, the fine tube is inclined 20 ° with respect to the vertical, and the diameter of the discharge port of the thin tube is set to 3 mm to 4 mm. Therefore, accurate fluidity can be applied to a granular material having a particle size of 45 μm to 850 μm. Can measure.

  Hereinafter, the present invention will be described with reference to the drawings. FIG. 1 shows a schematic configuration of a vibrating tube type powder body fluidity measuring apparatus according to the present invention. FIG. 1 (a) is a schematic diagram of the entire device in appearance. This apparatus is the same as the structure shown in FIG. 1 of WO 2006/115145 A1, which is the international publication described above, except for the structure described in detail as an example. Also, the basic operation of this apparatus is the same as that of the configuration shown in FIG. 1 of the above-mentioned International Publication, except for the operation described in detail as an embodiment. FIG. 1B shows a state until the narrow tube 10 in FIG. 1A is tilted by 20 ° with respect to the vertical by the angle adjusting mechanism 101. This granular material fluidity measuring apparatus 1 includes a hopper 11 for storing a granular material to be measured, a glass thin tube 10 for discharging the granular material, and a direction in which the glass thin tube 10 is perpendicular to the vertical direction of the thin tube. Piezoelectric element or vibrator 12 to be vibrated, a laser vibrometer 13 for measuring the vibration amplitude of a thin tube using a laser and a controller 14 for controlling the same, and a weigh scale (digital balance) for measuring the amount of discharged particles, that is, the weight 15 and a computer 20 for measuring and evaluating fluidity based on measurement signals from the laser vibrometer 13 and the weight meter 15. Reference numeral 100 denotes an outlet of the thin tube, and the tip is narrowed so that the discharge resistance of particles is maximized at the tip of the glass thin tube.

  A fluidity profile was used for measurement and evaluation of fluidity in the computer 20.

In the granular material fluidity measuring apparatus of FIG. 1 (a), the inner diameter of the glass capillary was set to 12 mm and the length was set to 180 mm. In the test of the granular material fluidity measuring apparatus, three types of capillaries with discharge port diameters of 2 mm, 3 mm, and 4 mm were prepared. The fluidity was measured under the same conditions for each.

In addition, instead of actual MOX particles, simulated particles were used. Simulated particles are amorphous particles of zirconia (particle density 5800 kg / mm ³ ), and the simulated particles are passed through a sieve and are 45 μm or less, 45 to 106 μm, 106 to 250 μm, 250 to 425 μm, 425 to 600 μm and 600 to 850 μm. After being classified into the above six particle size ranges, the main component and the mixed component were mixed in the combinations shown in Table 1 to obtain a measurement powder fluid sample.

The apparatus shown in FIG. 1 was set as described above, and measurement was performed according to the procedure shown in FIG. First, after adjusting the discharge port diameter and the inclination angle of the narrow tube (step S100), the discharge port is closed with a movable particle fall prevention plate (step S200), and in this state, sample particles are filled (step S300). In order to suppress the variation in the filling state, the vibrator 12 was vibrated for 25 seconds (vibration acceleration 300 m / s ² ) (step S400). Thereafter, the movable particle fall prevention plate is removed, the vibration frequency is made constant at 330 Hz (resonance frequency of the apparatus), the glass capillary 10 is vibrated by a sine wave whose amplitude increases at a constant rate, and the vibration amplitude of the glass capillary 10 is increased. While measuring with the vibrometer 13 using a laser beam, the mass flow rate of the particle | grains discharged | emitted was measured with the weigh scale 15 (S500). Then, based on the measurement signal of the vibration system 13 and the measurement signal of the weigh scale 15, a fluidity profile of the sample was obtained. In addition, the test time of 1 time is less than 1 minute, and after performing the test 3 times or more continuously, the average fluidity profile was calculated | required.

A typical fluidity profile of the sample particles determined as described above is shown in FIG. In the region where the vibration acceleration is small, the particles remain stationary, but when they exceed a certain value, the particles start to flow rapidly. As the acceleration is further increased, the mass flow rate tends to be almost constant or slightly increased. The straight line passing through the two points where the gradient of the fluidity profile is maximum (the one-dot chain line in FIG. 3) was extended, and the vibration acceleration at the point intersecting the x axis was defined as the flow closing initial acceleration (critical vibration acceleration in FIG. 3).

The relationship between the flow start acceleration (m / s ² ) and the average particle diameter (μm) measured as described above is shown in FIGS.

  FIG. 4 shows the relationship between the flow start acceleration and the average particle diameter when the inclination angle of the narrow tube is 0 °. The flow closing acceleration tends to decrease and take a local minimum and increase again as the particle diameter increases. This is because when the particle diameter is small, the adhesion is large, and thus a strong excitation force is required to start the flow of particles. When the particle diameter is large, the ratio of the discharge port diameter to the particle diameter is decreased, and the ratio of the circumferential length to the cross-sectional area is increased, which is considered to increase the resistance of the particles received from the tube wall.

  FIG. 5 is a graph showing the relationship between the flow start acceleration and the average particle diameter when the inclination angle of the narrow tube is 10 °. In this case, the same tendency as when the inclination angle was 0 ° was observed.

  FIG. 6 shows the relationship between the flow start acceleration and the average particle diameter when the inclination angle of the narrow tube is 20 °. When the discharge diameter of the narrow tube is 3 mm, the flow initiation distance does not become extremely large or small for all the samples used in this test, so particles from 45 μm to 850 μm It was found that stable fluidity evaluation is possible through the diameter range.

  As mentioned above, although this invention was demonstrated based on the suitable Example, this invention is not limited to this Example. For example, in the above-described embodiments, good results are obtained when the discharge port diameter of the thin tube is 3 mm and 4 mm. However, for example, substantially the same result can be obtained even when the discharge port diameter of the thin tube is 3.5 mm. It is clear.

It is a schematic block diagram of the granular material fluidity measuring device concerning the present invention. It is explanatory drawing of the granular material fluidity | liquidity measuring method which concerns on this invention. FIG. 3 shows a typical fluidity profile of sample particles used in the examples of the present invention. In the Example of this invention, it is the figure which showed the relationship between the flow start acceleration when an inclination angle of a thin tube is 0 degree, and an average particle diameter. In the Example of this invention, it is the figure which showed the relationship between the flow start acceleration and average particle diameter when the inclination | tilt angle of a thin tube is 10 degrees. In the Example of this invention, it is the figure which showed the relationship between the flow start acceleration when an inclination-angle of a thin tube was 20 degrees, and an average particle diameter.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Powder body fluidity measuring apparatus 10 Narrow tube 11 Hopper 12 Vibrator (piezoelectric element)
13 Laser Vibrometer 14 Controller 15 Weigh Scale (Digital Balance)
20 Computer 21 Display 100 Fine tube outlet 101 Fine tube angle adjustment mechanism

Claims (2)

This is a method for measuring the fluidity of a granular material using an oscillating capillary type granular material fluidity evaluation apparatus, wherein the capillary is vibrated at an angle of 20 ° with respect to the vertical, and the fine tube is moved from 45 μm to 850 μm. A predetermined amount of the granular material to be measured including the granular material to be measured having a particle diameter of at least 600 μm to 850 μm, the vibration amplitude of the capillary tube, and the Measuring the weight of the granular material discharged from a discharge port having a diameter of 3 mm to 4 mm, and determining the fluidity of the granular material based on the measured value. Method. The granular material fluidity | liquidity measuring method of Claim 1 WHEREIN: The said granular material is the MOX particle | grains granulated in the reprocessing process, The granular material fluidity | liquidity measuring method characterized by the above-mentioned.

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